Failed uploading, can't select a port

No any single pin has the same drive capacity.

This is most probably the case. Most relay boards however have built in drivers so that might not be a problem. However, if the relay is just a raw relay then you will not be able to turn it on with 3V3 (or even a 5V Arduino pin) unless you add your own relay driver, consisting of a npn transistor and a couple of resistors.