I can load it up and everything and I can sign in but when I click the green "+" symbol, nothing happens.

I also have this issue..

Click on the tab after you press +

You took my RSPS name... how could you.............

 

be patient and wait, it could just be java loading slow x.x

No tab comes up after I press the + I waited half an hour, I know because I finished an Office episode :P

Try this

1. Exit the client completely

2. Open a new client

3. Get signed out of your account on the client completely

4. Log back in on the client

5. Press the green "+" button to open a tab

6. The client should load.

Also, not being VIP, you can't have more than one tab open.

If you're getting the error message "your current subscription status does not permit any more tabs", then for whatever reason you client believes you already have an opened tab. 
If this happens, delete the client completely and re-download the newest version.

sidenote; this error is somewhat commonly found when using an outdated client. The bot may have also been [offline] and you may not have noticed.
 

sometimes the screen stays grey, just click on the #1 Bot or #2 #3 what ever