Today I was reported issues with the current template (that is recommended in the intro slides) as it is configured for a single-column layout.
You might use one of the following templates, which are double-column by default:
https://www.overleaf.com/latex/templates/association-for-computing-machinery-acm-sigplan-proceedings-template/rfvsrhgmghtc
https://www.overleaf.com/latex/templates/template-for-proceedings-of-the-vldb-endowment/krfrpvrbbvfj
https://github.com/cwida/pvldbstyle/archive/master.zip