I believe you mean Article IV, Section 4.
That provision (the guarantee clause) ensures that each state be run as a representative democracy.
Since the state allows its people to elect the state legislators, this requirement is met. Those elected representatives are then allowed to choose electors as they see fit.
The Constitution requires that the states be run as representational democracies, and that the senate and house are elected by the people - but it does not have that requirement for the electoral college members.
I disagree. Representatives cannot serve two masters.
To the extent that commentators acknowledge the issue, the conventional view is that states have absolute discretion to appoint their delegates in any manner they see fit...
...Disagreeing with this conventional wisdom, this Article concludes that the states lack the power to appoint their presidential electors on the basis of votes of citizens outside the states jurisdiction and, therefore, states are without authority to adopt the NPVC.
https://digitalcommons.law.byu.edu/cgi/viewcontent.cgi?article=2686&context=lawreview
And interestingly, Nebraska is the only state with a unicameral legislature.
-PJ