Dear Tayler,
Greetings! Thank you for posting in Microsoft Community. We are happy to help you.
Per your description, I understand you want to install Microsoft List desktop application.
You may let your colleague access Microsoft List by using Edge browser, firstly open Lists App from App Launcher, when you see the dialog box "New Lists Desktop App", click the Install button.
Or, you may click Settings from upper-right corner > Apps > Install Microsoft Lists.
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Feel free to let me know if you have further concerns, I'll be glad to help you further.
Thanks for your time and understanding! We hope you have a nice day, stay safe and healthy always.
Sincerely,
Tina | Microsoft Community Moderator