I am 90% convinced that the issue is linked with the specific computers. It cannot be the server if if is working on other laptops.
Are those users admin on their laptops?
If laptops are part of a domain, can they install apps?
Have you tried from another network, another wifi, another hotspot?
Have you tried to download the EXE client file from Marketplace and tried to install this one?
Please give kudos if it helps.