Hello! I recently faced a similar issue with discourse as well! On line 279 of the ./discourse-setup script, you will find a line that looks like this:
read_config_result=`echo $config_line | awk --field-separator":" '{print $2}'`
If you change the line to this:
read_config_result=`echo $config_line | awk -F":" '{print $2}'`
things should work.
I guess awk does not have the --field-separator parameter anymore.
If you do not wish to manually replace that line, you can just use this command below:
sed -i 's/--field-separator=/-F/g' ./discourse-setup
Hope this helps!