Do I have to stop to switch from 2wd to 4wd in 2004 rav 4?
Can I switch to 4wd while moving L like I can in my
Nissan pathfinder? Or come to a stop ?
Your year make & model appears to be 'full time 4wd' which means all wheels are driven all the time. The button you see on your dash is probably the "Center Diff Lock" button, which would lock the center diff, like in a 4wd truck with a selectable transfer case. It shouldn't be used on concrete. It could probably be engaged while moving below 10-15 mph, but you will probably find the information in the owner's manual.
The 2000-2006 RAV4 II does not have a button on the dash like the RAV 4.1 or RAV 4.3/4.4 it is always on and uses an automatic visco diff to lock it front or rear slippage is detected. One of the best 4wd systems used in these type of soft off roaders. Subru and the Audi R8 uses a similar system as well.