Can I use an electrolytic capacitor with a MCP1826S voltage regulator?
Yes, it's a bad idea.  This part is internally compensated and the compensation is expecting the ESR zero to be in a certain range.  If your output cap ESR is too high your converter may oscillate or react badly to transient load currents.

You can parallel several capacitors to get lower ESR, but in this case 5X4.7uF exceeds the 22uF maximum recommended output capacitance. 

So just go get the correct ceramic, poly or low ESR electrolytic.