Now the licensing part I don’t know, @RicardoE105, @jan or one of the others may be able to answer that part
I would say rather than having 100 workflows though depending on what the webhook passes in you might be able to do it with 1 and look up the customer details in Airtable or a database somewhere.
With the executions each triggered run is one execution so if woo commerce does one per order and you have 5 that would be 5 executions but if it has an option to group them together so call a web hook every hour then all 5 orders would be in one execution.
That is where using a cron trigger with the woo commerce get orders node may be handy as that would be one execution and you could process all orders.
Depending on if there are restrictions on what you can do with the cloud licensing you could offer your customers 2 tiers one “real-time” option that uses triggers and one that is a bit slower and uses the cron schedule.