I have a a Sound Librarie from Garritan, but i can’t use ist. I added the same Path like in Cubase 10.5 (C:\Program files\Steinberg\VSTPlugins\Garritan).
In Cubase i can use the library ind Dorico i can’t see it.
Have you whitelisted the Aria Player plug-in? If not, please refer to this article: https://helpcenter.steinberg.de/hc/en-us/articles/206899770-How-to-use-VST2-plug-ins-in-Dorico
There is also now VST3 version of Aria, though (as far as I can tell) you have to login to your MakeMusic account to download it. It is version 1.959 of the ARIA Player (not just the ARIA engine).
Also, the ARIA player really comes from a company named Plogue. Plogue offers, for free download, a one-voice player called “sforzando” which finds and honors all my installed Garritan libraries automatically. It now comes with a VST3 plug-in. As a one-voice player, in Dorico’s Play mode I add a separate instance of the sforzando vst instrument for each different player, instead of adding only one copy of ARIA and then programming it with multiple voices. I saved an end-point configuration and a playback template for the ensemble I often need and it loads them all easily when I need them again.
https://www.plogue.com/downloads.html (scroll down to find sforzando)
There was a thread about this recently. IIRC The VST3 version of Aria from the MakeMusic site also only plays back one MIDI channel, so whatever it is meant to be used for it isn’t a replacement for the VST2 Aria player in the Garritan orchestra and band libraries.
The VST2 Aria player works fine in Dorico so long as you get the blacklist/whitelist issues sorted out, and it is installed where that Dorico can find it, since unlike VST3s, there isn’t a single fixed location for VST2s,
Also Plogue sforzando might not understand all the non-standard extensions to the SFZ file format that Garritan use (and the fact that there is no complete and freely available documentation for either version doesn’t help either).
The VST3 can playback 16 MIDI channels! The VST3 ARIA plug-in only has one stereo output, rather than one stereo output for each MIDI channel, as the VST2 plug-in can.