When visiting a remote research facility, it is advised, among other things, to look at any online inventories or catalogs of what materials they have that could be helpful in your research.
That way you have an idea of what to ask for when you are there.
But don’t be afraid to ask for help when you are there or let them offer to help you. It’s very possible the facility has materials that are not inventoried, cataloged, or even mentioned online. A local person familiar with the collection may be able to give you guidance that you cannot get any where else.
It’s great to have a list of what you want to find and to search for it while you are at a facility, but it’s also a great idea to tell them what sort of things you are trying to find (what family and time period, etc.) and see if they have any suggestions.
None of us knows everything.