with a free account, you get a subscription, and $200 credit to use the first month. The account includes free services, but after using the initial $200, you need to pay for any non-free services.
to tell if correct credit available, login to port, select cost management, then payment methods. above the methods will be any credits. or click on the subscription, and under spending rate you will starting credit.
see free services:
https://azure.microsoft.com/en-us/pricing/free-services
for azure sql it is the b1 tier. you probably picked a higher tier. looks like its estimated to be 270 a month, so you could not get not quite a month of that service tier with your credit.