Hi,Simulacrum India
Welcome to Microsoft Community.
I understand that you can't find the option to upload in the Loop app.
Currently, Microsoft Loop's file upload feature is only available to Business Edition users. If you are using the Personal or Home Edition, you may not see the option to upload PDF files at this time.
Upload files to Loop workspaces - Microsoft Support
If you still can't find the upload option, it may be because the feature is not yet enabled in your account. We recommend that you check if you are using a Business Edition account or wait for the feature to be available in the Personal Edition.
In the meantime, Loop is currently in the preview experience phase, if you would like this feature to be rolled out in the Personal Edition, Microsoft takes the user experience very seriously and you can submit your ideas and suggestions through the Feedback Hub, where the development team will periodically review submissions or corrections.
Once submitted, please share the feedback link here as this will allow others on the forum to vote for your submission, including me. More votes will increase the attention and priority of the development team.
Looking forward your reply.
Best Regards,
Mila.L-MSFT| Microsoft Community Support Specialist