Factory Rest and Try to Reinstall El Capitan on my Macbook Pro 2011 "A REQUIRED DOWNLOAD IS MISSING" Pop Up

If you have an Early-2011 model then you cannot install El Capitan from scratch. You must first have Snow Leopard 10.6.6, .7, .8 or Lion installed first. If this fits your model, then you should have a software restore DVD or flash drive with the original software that came with the computer when it was new.

Snow Leopard Erase and Install

1. Insert Snow Leopard Installer DVD into the optical drive and restart the computer.
2. Immediately, at or before the chime, hold down the C key.
3. Release the key when the Apple logo appears and wait for the loading to finish.
4. After the installer loads select your language and click on the Continue button. When the menu bar appears select Disk Utility from the Utilities' menu. After Disk Utility loads select the out-dented disk entry from the side list (mfgr.'s ID and drive size.) Click on the Partition tab in the Disk Utility’s right window. Set the number of partitions to one (1) from the drop down menu. Click on the Options button and select GUID, click OK button, set the format type to MacOS Extended, Journaled. Finally, click on the Apply button.
5. After formatting has finished quit Disk Utility. Continue with the OS X installation and follow the directions.
6. When the installation has finished the computer will restart into the Setup Assistant. After you complete the Setup Assistant you will be running a fresh installation of Snow Leopard. Open Software Update and install any recommended updates.
7. If you are planning to sell or give your computer away, then do the following: After you reformat your hard drive and reinstall Snow Leopard, the computer restarts to a Welcome screen. To leave the Mac in an OOTB (Out Of The Box) state, don't continue with the setup. Instead, press Command and Q keys to shut down the computer. The Setup Assistant will guide the new owner through the setup process after he/she turns on the computer.
8. Download and install Mac OS X 10.6.8 Update Combo v1.1. if needed. It is not needed if you are selling or giving away the computer.

You can but if the drive has been completely wiped, then the installer may still hiccup because there is no Snow Leopard or Lion system already installed. On the other hand if your drive still has the Recovery HD partition installed, then you could try a straight recovery:

Reinstall El Capitan or Later

1. Restart the computer. Immediately, at or before the chime, hold down the Command and R keys until the Apple logo and progress bar appear. Wait until the Utility Menu appears.
2. Select Disk Utility and click on the Continue button.
3. Select the indented (usually, Macintosh HD) volume entry from the side list.
4. Click on the First Aid button in Disk Utility's toolbar. Wait until the Done button activates, then click on it.
5. Quit Disk Utility and return to the Utility Menu.
6. Select Install OS X and click on the Continue button.

This will install the last version of macOS installed on the computer.