He sure as hell riled people up and he set the seeds for what happened and has a degree of culpability for what happened. However in regards to the specific question "Did Trump Tell Supporters to Storm US Capitol on Jan. 6, 2021?" the answer is No. Intermediate ratings on fact checkers are what are used to slip bias into what are not very ambiguous situations, because you can say "Yes, but..." or "No, but..."
The good thing about fact checkers, and the reason I generally support them even if I don't see them quite as neutral, is at least they write down the facts so you can come to your own judgement. I just ignore the ratings they give at this point, the articles are much better.
I agree that Trump did not explicitly tell his supporters to Storm the Capitol, as does Snopes.
The grey area is in the riling up you talk about and the phrasing of the question.
Tell/told is often used to convey meaning rather than literal instructions, so I understand why they have stated this is mixed.
It all feels very post-truth to me and seeing a fact checker endorse this sort of view is absolutely depressing in a way. These are institutions of which there is broad support for making the arbiters of truth on social media for whom truth is subject to subjective interpretation. In which case what's the point of fact checking at all?
This free interpretation of words uses a new (repurposed) trendy term too: "dog whistle". Suddenly you are free to interpret anything one says in the most negative light, just by claiming it's a "dogwhistling" for some group or action you despise.
Snopes also claims that this vote is "ceremonial", yet it was used in the aftermath of the civil war to disenfranchise every southern state which sent electors; that doesn't sound very "ceremonial" to me.
Arguably both of these issues are immaterial to the rating, but then why include them at all? And why trust a fact checker who is demonstrably spreading misinformation themselves, however immaterial it may be?