Assume that zenloop sold a 20% equity stake to the investors.
Then zenloop is valued at €5.3M / 20% = €26M post-money.
Assume that this was a Series A.
And that the investors want to make 5x on their investment.
And that there will be 1 follow-up round of 20%.
Then zenloop must have a €26M * (5 / (1–20%)) = €165M exit value for its €26M valuation.
Assume that zenloop trades at 4x trailing 12 months revenue at exit.
And that there will be no cash and debt.
Then zenloop must have an average €165M / 4 / 12 = €3.4M in monthly revenue for its €26M valuation.
Zenloop charges startups €299 per subscription per month.
Then zenloop must invoice €3.4M / €299 = 11,000 subscriptions per month for its €26M valuation.
For context: Germany had 357,000 small companies in 2018.