for 1st one, one thing is clear that its identifying you already have 2 servers as part of your HA pool so you cannot add any more. 1 HA pool can have only 2 members( servers).
Yon can check this thread where its explained how to setup HA very clearly: Multi-Subnet Failover (WAN/DR) Deployment
Regarding second one: it could be a browser issue or try running the configuration wizard once.
That second one looks like you using firefox to access VMware to control a server then using ie on that box to access Solarwinds.
seems odd can you not just access the url from your pc rather than VMware.
just in case some odd issue with that.