Deciding if you need to make estimated tax payments

I am helping a friend with her taxes. The following is a quote from the instructions for form 1040ES:

In most cases, you must pay estimated tax for 2021 if both
of the following apply.

1. You expect to owe at least $1,000 in tax for 2021,
   after subtracting your withholding and refundable credits.
2. You expect your withholding and refundable credits
   to be less than the smaller of:
   a. 90% of the tax to be shown on your 2021 tax return,
   or
   b. 100% of the tax shown on your 2020 tax return.
   Your 2020 tax return must cover all 12 months.

The person is self-employed and just started her business in 2020. In 2020, she had less than 5000 of self-employment income. She is anticipating that she will report a significant amount of self-employment income in 2021.

Line 24 of her 1040 says:
24 Add lines 22 and 23. This is your total tax 1,344.

However due to credits, e.g. credits related to her health insurance, she owes no taxes this year. In fact she is getting a refund which is larger than her withholding. I am thinking that she does not have to make any estimated tax payments in 2021. That is, she does not have to pay any income tax until April 2022 even if she makes 200K from self-employment and she will not have to pay a penalty. Do I have that right?

I am tempted to say that she needs to pay 1,344 through out the year in 4 payments to avoid a penalty.

The person lives in the United States.