Hillary Clinton has deep ties with many governments and business interests around the World. Saudi Arabia could see that donating money to Clinton's campaign might help them in the future. The Saudis could see their donations like an investment in her presidency. That way, if elected president, she might take more favorable actions when dealing with the Saudis.
The activities of the Clinton Foundation have been shady for a long time, and became even more suspect when it was discovered that the Foundation was receiving donations from countries we often view as our enemies...such as Saudi Arabia. The fact that the Foundation didn't turn down these donations leads me to believe that they would welcome more support from that country, specifically in the form of financial contributions to Hillary Clinton's campaign war chest.
I am sure she is getting money from Saudi Arabia, along with Republican nominees also. That is the way the political world works. It is all about money and who has the most of it and what do they want so you can get some of it. Money makes politics go around.
No, it does not make sense to believe that Saudi Arabia would fund Hilary Clinton's campaign. Saudi Arabia has no connection to Hilary Clinton that would make them fund Hilary Clinton's campaign. There are a lot of more logical places that may fund Hilary Clinton's campaign than Saudi Arabia. No one should believe this.