Pardon the brevity of the response, but, perhaps, I can touch on the ‘cliff notes’ to this subject as there is certainly much more to be said here, and I will undoubtedly leave lacunae. Now, I cannot speak to Deleuze, however, regarding Spinoza, it depends on what you mean by ‘act freely’. If by this you mean, ‘free will’ in the sense of the supposed ability of humans to make choices/actions independently of any antecedent -then, the answer is, you cannot, ‘act freely’. For this would still fall under the ‘imaginary’ form of knowledge within Spinoza’s epistemology. That is to say, the knowledge that one would have of the ‘notion of freedom’ would be a deformed one, of sorts. Strictly speaking, the only one, or thing, that can ‘act freely’ in an absolute sense, is God or nature. “that thing is said to be free which exists solely from the necessity of its own nature, and is determined to action by itself alone" (EID7). nature/god is the causa sui. The cause of itself I.e dependent upon nothing else, nor anything outside itself. Unlike a human being, who is dependent upon things outside itself and antecedents before itself.

For the human agent, the way to ‘act freely’ if one follows, or at least provisionally accept Spinoza’s argument hitherto, one would find freedom in increasing/expanding our ‘joy’=‘power of acting’. We do this by coming to understand the ‘adequate causes’, that is, the necessity of things within nature, or God. Naively, the answer is, the more you understand the adequate causes of things the more one ‘knows’ and from this increase in knowing, we are more able to ‘act’ freely in the first place.

As I said, I’m no expert, and no doubt much more could be added here, but, I hope at the very least this may shed some clarity on your query.

Moreover,the subject of Freedom in Spinoza is a deeply rich and fascinating subject with varying degrees of scholarly discordance.

If you are looking for a supremely clear, erudite and authoritative account on Spinoza, I urge you to read essentially any book by Steven Nadler.

https://philosophy.wisc.edu/staff/nadler-steven/

However, for your seeming immediate purposes, his book entitled: Spinoza's 'Ethics': An Introduction (Cambridge Introductions to Key Philosophical Texts), is likely the way to go. I cannot think of a better ‘trail guide’ to take into the magnificent labyrinth of the Ethics.

Happy reading/learning, and remember: “all things excellent are as difficult as they are rare”. Cheers