You may be right, it may be necessary to install a small 12v battery to complete the circuit, shortly after that you may wanna check for spark
Did you clean the carburetor?
Did the engine run before the last owner gave it to you?
If so, then install a new battery, prime the fuel to make sure there are no air pockets in the fuel line, pull the choke up and fire that puppy up, hook up a spark tester to make sure you’re getting spark, if not then start looking at your wiring harness and coil. That would be a good place to start.