Hi.
Ah, probably the packages are not supporting 2019 yet.
Do you have a particular reason to use 2019?
It is always better to use a unity version at least 1 or 2 major versions before the latest, unless you really need something from the latest version.
Main reason is that many assets still need to update for that version and also there can be still many bugs in it.
Can you try with unity 2018.3 if you see them there?
Btw. if you want to use multiple versions of unity you can use
Unity Hub