I’ve downloaded synth v basic a few days ago to make a song , but I don’t really know much about the software and i just want to know how much much of a length i can make in the basic edition
The only limit to the length of a song is if you are using an FLT (Feature-Limited Trial) voice database (ie the free versions of Ritchy, D-Lin, or Eri). These are limited to 45 seconds of output.
There is no limit on project length for using the Basic edition or a lite voice database.
You can see all the differences between Basic and Pro here: