Learn Dutch: Het project zal veel tijd vereisen om te kunnen slagen. - The project will require a lot of time to be able to succeed.

When an om ... te (in order to) clause has multiple infinitives at the end, te always goes immediately in front of the first infinitive in the cluster. Here, the modal verb kunnen acts as the auxiliary to the main verb slagen, so te must go right before kunnen.

Could I say om te slagen here instead of om te kunnen slagen?

Yes, but it changes the meaning slightly. Using om te slagen simply means 'in order to succeed'. Adding kunnen makes it 'in order to be able to succeed', emphasizing that the extra time is required just to make success a possibility.

Is vereisen a separable verb?

No, it is inseparable. Verbs starting with unstressed prefixes like be-, ge-, er-, her-, ont-, or ver- do not split. If you used this in a simple present tense sentence without zal, it would stay together: Het project vereist veel tijd.

Why does the om ... te clause come after the infinitive vereisen?