You can find the checklist for HA on Connect in the admin guide at https://docs.rstudio.com/connect/admin/load-balancing/#high-availability-load-balancing
Our best practise recommendation is to run each product on it's own server. This ensures that you can easily scale the server for the load that is being placed on it by that single product. For this reason the downloads and installers are separate, and not bundled. See https://docs.rstudio.com/installation/ .
For RStudio Connect as well as Package Manager you must provide your own load balancer (with sticky session support). AWS ALB should work fine, but your own team should evaluate and configure this. Unfortunately RStudio can't provide guidance for configuration of ALB.
Both of these products require a PostGres instance, that your DBA should provide and maintain (including backup, HA, etc). However, the creation of tables on these instances is managed by the RStudio products, so your DBAs will not have to create tables or schemas. See https://docs.rstudio.com/connect/admin/database/postgres/ and https://docs.rstudio.com/rspm/admin/database/#database-postgres