TurboTax Online asking to double-click to link to Schedule C. I have one 1099-K, but imported additional credit card income separately under 1099-K (no 1099-K issued).

You are not required to report the credit card income separately.  You are not required to enter the credit card income under other income.  

However, if you do report the credit card income separately, the credit card income not reported on an IRS form 1099-K may be reported under an income line within the self-employment activity.

The credit card income which is reported on an IRS form 1099-K may be entered within the self-employment activity.  In TurboTax Online, follow these steps.

• Down the left side of the screen, click Federal.
• Down the left side of the screen, click Wages & Income.
• Click the down arrow to the right of Self-employment.
• Click to the right of Self-employment income and expenses.
• At the screen Your 2024 self-employed work summary, click Edit to the right of the self-employment activity.
• At the screen Here's your info, select Add income for this work.
• At the screen Let's enter the income for your work, select Form 1099-K.