The UI Vision command line does not have a loop parameter because you can integrate the loops into the macro itself, see here: Missing CSV loop functionality with Kantu v5.0.1 - #2 by admin
If you want to send a certain loop value (e. g. 20) to the macro, you can use the cmd_var1 switch, and then use ${!cmd_var1} in your WHILE-loop.
cmd_var1=hello%21world, cmd_var2, cmd_var3 - Send values to a Kantu macro from the command line. Inside the macro you can access the value with the internal variables ${!cmd_var1}, ${!cmd_var2} and ${!cmd_var3}