Hi there,
Thanks for reaching out. This shouldn't be happening.
I'd like to inform you that Adobe Express has the ability to automatically save the projects as you work.
Any project the creator has worked on comes under the project section on the Adobe Express web. (Please refer to the screenshot)

Firstly, I'd recommend you to check if the Adobe ID on the mobile device and the Mac system are the same.
If that isn't the issue and still the projects are not available on the Mac, you may try the following steps:
- Clearing the cache/cookies of the browser you're using.
- Signing in from a different browser or incognito/private mode.
- Signing out and then back in Adobe Express.
Note: The Adobe ID used on both mobile and Mac should be the same for projects to sync & be readily available to use anytime.
Let us know if this helps.
Regards,
Amitej