Same problem. Upgraded to 2.03.18 on my Synology DSM 1515+ running DSM 5.2-5644 Update 5. After I open Idrive and authenticate against my Synology, I get a spinning circle. If I try another browser and try authenticating against my Synology, I get "Application already in use" even if I stop Idrive in Package Center.
Figured I'd then try upgrading to DSM 6 and DSM tells me that Idrive is not supported (even with 2.03.18 being installed.
This needs to be resolved very quickly.