You can do a search for your type of work by clicking the blue Lookup Business Codes option. And if you don't see anything that matches, just put in 999999, which is miscellaneous. It's not something the IRS needs nor will it have an affect on your return.
This one is closest related to your line of work, but it's not required to use it. You can just use the 999999 if you prefer.
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Taxi & limousine service (485300)
"Taxi Service, Limousine Service"
https://ttlc.intuit.com/replies/3300135