The RoomPacks downloads are supported by VSL's Download Manager, which should also start its installation. If it doesn't, please start VSL's Library Installer appIication manually.
In case you have decided to change the installation path to a custom location, please make sure to point MIR Pro to it later on. The default installation path is [WIN] <SystemDisk>\ProgramData\VSL\Vienna MIR; [OS X] Macintosh HD/Library/Application Support/VSL/Vienna MIR.
After installation, the file will be called "Vienna_Konzerthaus_Mozartsaal_Trial_v2-r263.vmi". It should be 217 MB in size (about 228,000,000 KB). The extension *.vmi stands for Vienna MIR Impulse-response data.
... please make sure that MIR Pro's Preferences point to this file.
Kind regards,