If you n need to use a knee scooter for 2 or more months I strongly recommend that you invest in the Vevor Knee Scooter. A far a better quality than you will find at a mobility rental centre.
I m 6'3" tall and did not have any issues in setting up my scooter. There is some final assembly required, NO TOOLS NEEDED. You will need to inflate the tyres to the correct pressure, which you will find on the side wall of the tyres. A car tyre pump will do the trick in a short time, or a bicycle tyre pump will be the same, as long as you have a tyre pressure gauge. You could also take it to your local petrol/service station. Just be mindful of the inflation pressure.
The model I bought was the aluminium version, very solid and still has some weight, but you get used to that in a short time. With the ability to extend the frame, I found going down a step or street getter was better, because I didn't feel that is was going to do a nose dive.
The other safety factor I love about the Vevor scooter were the brakes. Far more superior to the rental models.