File size limits
Adding files to Gumroad should be as easy as selling on Gumroad, so...
If you price your product at any number greater than $0
In other words, your product costs 99¢, $1, $1.01, $1.02, etc. etc. etc.
Then you can make your product as big as you like.
The largest SINGLE file that you can upload to a product is 16 GB in size. We rarely see anyone upload files larger than 5GB, so that shouldn't be an issue for the vast majority of creators.
Therefore, if you were so inclined, and absolutely hated your customers, then you could upload 100 files, all 16GB in size. We wouldn't recommend it, but you could do it.
If you price your product at $0+
In other words, if you're using our Pay What You Want feature, and setting the lowest possible price to be $0, then the max product size can be 250 MB.