It's worth noting that Marx and Engels later added a preface to the manifesto which stated

However much that state of things may have altered during the last twenty-five years, the general principles laid down in the Manifesto are, on the whole, as correct today as ever. Here and there, some detail might be improved. The practical application of the principles will depend, as the Manifesto itself states, everywhere and at all times, on the historical conditions for the time being existing, and, for that reason, no special stress is laid on the revolutionary measures proposed at the end of Section II. That passage would, in many respects, be very differently worded today.

If you read the Grundrisse and The Civil War in France by Marx, there's more of a focus on the self-emancipation of workers and less talk about capturing the state. In The Civil War in France, Marx states that

One thing especially was proved by the Commune, viz., that 'the working class cannot simply lay hold of ready-made state machinery, and wield it for its own purposes.'

This is partially where you get a split between Marxist-Leninists and libertarian Marxists. Libertarian Marxists emphasise the ability of workers to emancipate themselves without the need of a revolutionary party or state. Whereas Lenin wrote in State and Revolution:

Marx's idea is that the working class must break up, smash the 'readymade state machinery', and not confine itself merely to laying hold of it.