I have some experience with bringing museum exhibits online, and unfortunately this experience is total standard. Museums think they own their artefacts, and they want to control who gets to "publish" them. Typically museums have a few archaeologists that they have close ties with who get the privilege of publishing stuff. If some random person comes along, god forbid from abroad, they will try everything to stop you…
Yep, I work in this area and museums/libraries often believe that they have the right to prevent you from using the creative works whose originals they physically hold. This is usually not the case. And in the vast majority of countries, digitizations of at least 2D works aren't able to be copyrighted.
If you wanna know more, you should look at the one time the National Portrait Gallery threatened to sue Wikimedia[0] for having an archive of uncopyrighted material. It went nowhere - primarily because the US has soundly and firmly rejected the nonsense that "sweat of the brow" creates copyright. Hell, even the EU doesn't think you can recopyright public domain works this way. But the UK-hosted NPG is still asserting primacy of UK law over the whole Internet to this day.
[0] https://en.wikipedia.org/wiki/National_Portrait_Gallery_and_...