How to run the program to find a hash

I found a problem which asked to find a string that its MD-5 hash is 68468614ed2e2a05c44a8824748a2742. It was said that the string has 11 letters from a to z. How can I find it using hashcat? I wrote that has to the file hash.txt. I downloaded the latest beta and tried to run it with

./hashcat64.bin hash.txt -O -w 3 -a 3 ?l?l?l?l?l?l?l?l?l?l?l

the output was


hashcat (v3.6.0-444-g9de1e557) starting...

Cannot find an OpenCL ICD loader library.

You are probably missing the native OpenCL runtime or driver for your platform.

* AMD GPUs on Linux require this runtime and/or driver:
  "AMDGPU-PRO Driver" (16.40 or later)
* Intel CPUs require this runtime and/or driver:
  "OpenCL Runtime for Intel Core and Intel Xeon Processors" (16.1.1 or later)
* Intel GPUs on Linux require this runtime and/or driver:
  "OpenCL 2.0 GPU Driver Package for Linux" (2.0 or later)
* NVIDIA GPUs require this runtime and/or driver:
  "NVIDIA Driver" (367.x or later)

Started: Mon Aug 28 14:03:20 2017
Stopped: Mon Aug 28 14:03:20 2017

Here is some information on my GPU:

lspci -v |less outputs

00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
        Subsystem: Acer Incorporated [ALI] Haswell-ULT Integrated Graphics Controller
        Flags: bus master, fast devsel, latency 0, IRQ 44
        Memory at b0000000 (64-bit, non-prefetchable) [size=4M]
        Memory at a0000000 (64-bit, prefetchable) [size=256M]
        I/O ports at 3000 [size=64]
        [virtual] Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: <access denied>
        Kernel driver in use: i915
        Kernel modules: i915