I had Home Studio 2002 for a few years until it would no longer install on new PCs (I think around the WinXP era, when I went from 32 to 64-bits...). Then I went without any version for a few years, then bought Music Creator 7 off of Steam in early 2016. My sound card is a Sound Blaster Audigy RX, which is not an audiophile card but is still better than the mobo sound.
 
I've used Music Creator a few times since buying it and had no issues with it.
Now when trying to export a mixdown (bounce-to-track) from Music Creator 7, I get a message that says something like "No Windows streaming media codec available". There is no other audio file format to export as.
 
My PC is running Win10 x64 and has the creators' update, that I read disabled Windows Media Player--which I have not yet enabled. Is this message just because of WMP being disabled? Or is it some other error? Even though Music Creator 7 will not export (at all) I can use the Soundblaster-specific recording program (Smart Recorder) to record the PC's system mixer and Smart Recorder can still save as wma without any problems.
 
Also I am curious if there is a plugin or anything else to export sound into different formats directly, such as MP3... Since the product name has changed and now gone back, the product page for Music Creator goes to Home Studio (2017). I can't get to any Creative site page specifically for Home Studio 2017 now, it seems.
 

As you mentioned some Windows 10 versions do not include a media player however you can go to Microsoft Windows 10 downloads and obtain a free media player.
 
Cakewalk provides a MP3 encoder with Sonar and the current Home Studio is in the Sonar family.  The encoder works for thirty days and then you must purchase a key to unlock the encoder.  A search of Cakewalk's Knowledge guide reveals "MP3 export is now (as of April, 2017) available in SONAR Artist, Professional, and Platinum at no charge."   If you don't want to worry about the Cakewalk MP3 encoder turning off after thirty days you can find the free open source LAME MP3 encoder on a web search.
 
The Music Creator 7 you purchased is available as both 32 and 64 bit programs while the Home Studio 2002 program only has a 32 bit program.  If you downloaded MC7 using a computer running a 64 bit operating system the download will automatically be 64 bit bit if the operating system is 32 bit you will receive the 32 bit program.  While both 32 and 64 bit programs should work on a 64 bit system I would make sure you are using a program that matches the computer operating system.
 
If you are using a Creative card in your computer, Creative doesn't provide Windows 10 drivers for any card that has a game / midi port.  Creative stopped supporting cards with game ports with Windows 7.

Cakewalk made mp3 free for all Cakewalk users. I am not sure if the unlock program provided here works with products sold on Steam. That would be a question for the Steam discussion area.

scook Cakewalk made mp3 free for all Cakewalk users. I am not sure if the unlock program provided here works with products sold on Steam. That would be a question for the Steam discussion area.

I appreciate you providing the link to the MP3 Encoder unlock program.  Look at my post above and you'll see a quote I copied from the Cakewalk Knowledge Guide.  The quote lists SPECIFIC Sonar products that Cakewalk listed to use the "free" unlock program.  Home Studio, Music Creator and earlier Cakewalk releases are not listed.  If this quote is incorrect please ask Cakewalk to correct the information so others that try to help will not provide wrong information.

Depends on the version. I found this image from an old store page that details which Cakewalk products use the unlock program -

Note: this image predates the current SONAR Home Studio/Artist/Professional and Platinum which all use the same unlock program.

The MP3 unlock that you can download from the website site is the same one we use for Steam. So it's all the same.

We added the Mp3 activators to everyone's Steam packages on Steam back in April. It should be under your MC7 DLC listing. If it isn't please let me know and I'll double check them.

I think the "no streaming Windows media codec" message is related to exporting WMP though. Have you tried Mp3 or Wave?