I'm not sure why the chat closed, but we can continue this way.
There are a couple of different problems here. First, the transmission warning message. This is caused when the transmission control module detects a fault in the system. This could be anything from a bad speed sensor, wiring problem, shift solenoid problem, internal slippage of the transmission, etc. This is causing the transmission to go into what is called "Limp Home Mode", which keeps it in third gear to prevent damage. You need to have the trouble codes read in order to have an idea of what is going on. I will say, however, that those transmissions have seen quite a few problems, though mostly in the XC90s.
The low oil pressure light and check engine light are likely related. Low oil pressure can be caused by clogged oil passages in the engine due to sludge. The engine is equipped with Continuously Variable Valve Timing. This system uses oil pressure to change cam timing based on engine load. Because it runs on oil pressure, if there is a restriction, the CVVT solenoid won't function properly and this can cause the check engine light. Again, codes will need to be read in order to know which direction to go with diagnosis. In the meantime, make sure the oil level is full and clean.
Volvo has a new service program called "Volvo Service For Life", which gives the customer up to one hour of free diagnostics for any warning light or warning message. I would recommend taking advantage of this program to have one of these lights diagnosed. Since they are separate systems, they may charge 1 hour to look at the other warning message. But if its something relatively easy, they may not charge the hour once they read the codes to have a better idea what is going on.
Let me know if you have any other questions.