Try:
$Version
(*"13.0.0 for Microsoft Windows (64-bit) (December 3, 2021)"*)
ClearAll["`*"]; Remove["`*"];
a = Rationalize[0.0021, 0];
b = Rationalize[1.38889, 0];
c = Rationalize[6.94444, 0];
d = Rationalize[-4.125, 0];
ysol = NDSolve[{y''[x] == -4 *Pi*a*Exp[-y[x]] + 4*Pi*a*Exp[y[x]],
y'[c] == 0, y'[b] == d}, y, {x, b, c},
Method -> {"BoundaryValues" -> {"Shooting",
"StartingInitialConditions" -> {y[c] == Rationalize[1.653, 0],
y'[c] == 0}}}, WorkingPrecision -> 50]; Plot[{y[x] /. ysol,
y'[x] /. ysol}, {x, b, c}, PlotLabels -> {"y[x]", "y'[x]"}]
{y'[x] /. ysol /. x -> c, y'[x] /. ysol /. x -> b}
Or:
ysol1 = NDSolve[{y''[x] == -4 *Pi*a*Exp[-y[x]] + 4*Pi*a*Exp[y[x]],
y'[c] == 0, y'[b] == d}, y, {x, b, c},
Method -> {"BoundaryValues" -> {"Shooting",
"StartingInitialConditions" -> {y[b] == Rationalize[5.792, 0],
y'[b] == d}}}, WorkingPrecision -> 50]; Plot[{y[x] /. ysol1,
y'[x] /. ysol1}, {x, b, c}, PlotLabels -> {"y[x]", "y'[x]"}]
{y'[x] /. ysol1 /. x -> c, y'[x] /. ysol1 /. x -> b}
Or:
ysol3 = NDSolve[{y''[x] == (-4*Pi*a*Exp[-y[x]] + a*4*Pi*Exp[y[x]]) +
NeumannValue[0, x == c] + NeumannValue[d, x == b]}, y, {x, b, c},
Method -> {"FiniteElement", "InterpolationOrder" -> {y -> 2},
"IntegrationOrder" -> 5,
"MeshOptions" -> {MaxCellMeasure -> 0.001}},
InitialSeeding -> {y[x] == x}]
Plot[{y[x] /. ysol3, y'[x] /. ysol3}, {x, b, c},
PlotLabels -> {"y[x]", "y'[x]"}]
{y'[x] /. ysol3 /. x -> c, y'[x] /. ysol3 /. x -> b}
Regards.