I can't seem to find a option to pay for the GBC rom to download, can only see the physical copies and  play in browser,

There is no option--I'm not interested in physical either. Because I have a flashcart I can load it onto.

There was a download some months ago. Unfortunately when they got a publisher for a physical version, they removed it here. I purchased it and can't download it anymore myself... and the publisher doesn't offer digital versions either :(