Trying to upload a file to a site, but files are greyed out

I am posting this because after hours of talking with support, trying to contact the website admin, I finally figured out a solution. We have to upload document to a site, and there is a pop up menu that says “Choose a File” when we click on it, we can see all the files, but cannot select them like we normally do on our MacBook, the files are all greyed out.

I finally figured it out that if I shrink the web browser and open the file app, I am able to drag and drop the files in place. I hope this helps someone!!!

But I can select the files and drag and drop into place if I do a split screen with the webpage and File app