Depends, one for sure and maybe two but not more.

One and a half.

i did two no probelms

I manage 2, though I'm fairly skimping on the amout I use as I find it sticks well enough with one coat of cement on the rim alone.

one

I've been told two however I'm not sure if I used half a tub when I fitted one tyre recently, and I didn't skimp when applying. It's not the biggest tub of glue but I've got mine as back-up in case I run out of tape.

I've used on carbon rims and it worked ok

There is a glue for metailc rims and a separate Continental glue specific for Carbon Rims, Cheers!

Just coat the rim but clean the rim first-if old glue there this can be tricky but some petrol on a rag will take it off! most glues suggest one coat then leave to get sticky (10-15 mins) then a second coat leave for another 10 mins then put the tub on and make sure it is centered-inflate but not too hard then leave overnight and inflate more before you ride.